The present invention relates to means enabling the escape of personnel from vehicles and craft, particularly aircraft, and especially through canopies and windscreens.
Aircrew escape from modern high speed aircraft is generally achieved with an ejection seat which projects its occupant out of the aircraft at a high speed and trajectory commensurate with the need to avoid impact with other parts of the fuselage, to reduce the effects of air blast, and to carry the occupant well clear of a possibly exploding aircraft. It is thus requisite that the usual canopy above the head of the airman be opened as rapidly as possible, usually faster than for normal entry or exit. In order to do this the canopy may be opened or removed bodily by mechanisms similar to that used for the ejection seat, even this may not be sufficiently rapid. Appreciable time can be saved if, instead of removing the canopy as a whole, an opening is cut in it through which seat and occupant can pass. This in itself presents difficulties since canopies are usually made of tough material to withstand cabin pressurisation and impact by birds etc.
One apparatus for cutting an opening in a cockpit canopy involves the use of explosive cord such as is described in U.S. Pat. No. 3,806,069. Because of the toughness of the canopy this is however apt to be bulky and thus liable to restrict vision. Moreover its operation can entail spattering of the person with undesirable substances. It is also difficult of testing, over a long term, that a particular installation is still viable.